One of the most instantly recognisable icons in cinema, Marilyn Monroe, is currently the subject of special season at the BFI on Southbank. Running until the end of the month, the line-up includes comedies such as Some Like It Hot and Gentlemen Prefer Blondes. Her more serious work is represented by what turned out to be her last completed film, The Misfits (1961), which is also re-released in…